Contemporary American diagnostic systems vary considerably in their definitions of psychotic depression, schizo-affective depression and schizophrenia. Even within individual systems these conditions may be more difficult to distinguish than others. A failure to fully appreciate these difficulties may account in large part for the uneven success of efforts to biologically discriminate psychotic depression from schizphrenia. We propose, therefore, the emphasize diagnostic rigor in a study of clinical course and neroendocrine test results among consecutively admitted patients with nonmantic functional psychosis. Seventy consecutive admissions with nonmanic functional psychosis who meet certain additional inclusion criteria will be given a detailed structured interview (SADS) and a neroendocrine test battery involving the dexamethasone suppression test (DST) and the thyroid releasing hormone stimulation test (TRH-ST). The principle investigator will use information from the SADS, from all clinical records and from his own unstructured interview to assign diagnoses in three systems - DSM-III, RDC and the criteria of Feighner et al. The research assistant will then evaluate subjects at six month intervals for a period of one year with semistructured instruments of established reliability. Another senior clinician, blind to neuroendocrine test results, will then re-interview these patients and use clinical data collected at intake and during the follow-up to reach and independent rediagnosis in each of the above three systems. Twenty-one patients have completed the intake battery in the course of a six month pilot study. Preliminary findings confirm the diagnostic discordance across the above three systems predicted by earlier studies. Cell sizes have been projected from these pilot data; power analyses show that the proposed sample size is adequate to test the listed hypotheses. This design will thoroughly assess the practical value of these two neuroendocrine tests to clinicians faced with critical diagnostic distinctions. Furthermore, we will compare the relative validity of these three diagnostic systems as measured by course differences, neuroendocrine test results and final diagnosis. Finally, relationships between HPT axis abnormalities and HPA axis abnormalities will be studied within select diagnostic groups.